The respiratory and circulatory effects of immersion and release from immersion will be studied in the term lamb. A physiologic state similar to that in utero will be preserved by delivering a lamb by hysterotomy into a pool of water at amniotic temperature while the umbilical blood flow is preserved. Respiratory and circulatory changes will be observed while selective areas of the lamb's face and respiratory tract are released from immersion and stimulated. If breathing occurs, these areas will be selectively moistened or reimmersed in order to observe changes in respiration and circulation under these circumstances. The breathing lamb will also be observed similarly during selective immersion of these regions. Additional studies will attempt to separate the effects of hypercarbia from those of hypoxia in the fetus subjected to partial asphyxiation. The studies will be directed toward obtaining information which may prove useful in neonatal resuscitation.